1. Field of the Invention
A method is described for establishing two redundant Switched Virtual Channel (SVC) connections through ATM Networks using the same ATM End System Address (AESA) from a source ATM End Point to a destination ATM End Point.
2. Description of Related Art
ATM (Asynchronous Transfer Mode) is a term typically used to describe a high-speed, cell-switching network for LANs and WANs that handles data in real-time voice and video. It generally combines the high efficiency of packet switching used in data networks, with the guaranteed bandwidth of circuit switching used in voice networks. ATM is widely used as a network backbone in large enterprises, communications carriers and Internet Service Providers (ISPs).
There are a number of relevant international and U.S. standards and recommendations for ATM networks, including the following:
ITU-T Recommendation I.630 (02/1999), “ATM Protection Switching”;
ITU-T Recommendation Q.2931 (02/1995), “Broadband integrated Services Digital Network (B-ISDN)—Digital Subscriber Signaling System No. 2 (DSS2)—User-Network Interface (UNI) Layer 3 Specification for Basic Call/Connection Control”;
ATM Form Standard AF-SIG-0061.000 (07/1996), “ATM UNI 4.0 Signaling Specification”;
ATM Form Standard AF-UNI-0010.002 (09/1994), “ATM UNI 3.1 Signaling Specification”; and,
ATM Form Standard AF-PNNI-0055.000 (09/1996), “ATM PNNI Specification Version 1.0”.
In a typical data transmission system, information is transmitted over redundant connecting lines. It is critical, however, that such systems be robust so that the network experiences the minimum of downtime.
One approach is described in WIPO Publication WO 01/03360 entitled “Method for Switching Transmission Units to an Equivalent Circuit in a Packet or Unit Transmission” and assigned to Siemens Aktiengesellschaft. According to that invention, the priority information, which is allocated to each IP packet in the TOS field is used to route the relevant IP packet via either an active or the redundant connecting line. If a malfunction occurs, the transmission units are switched over to the redundant connecting line and high-priority IP packets take precedence over the IP packets with a lower priority.
Similarly WIPO Publication WO 98/04097 entitled “High Availability ATM Virtual Connections” describes a method of establishing and maintaining a connection through an asynchronous cell based network having a plurality of switching nodes such that when the source end point receives an indication that the destination end point has transferred to the alternate path, it sends cells from the source end point to the destination end point to complete the transfer to the alternate path.
Another approach is described in U.S. Pat. No. 6,226,260 entitled “Method and System For Resilient Frame Relay Network Interconnection” which describes, in part, a standard protocol which allows a network-to-network interface (NNI) to automatically respond to physical interface failures detected by the self-healing network.
While the foregoing prior art techniques address the question of improved resiliency in various types of data transport networks, nevertheless, some approaches require additional hardware and others are not optimally efficient for Voice over ATM (VoATM) applications based on Softswitch call model.
It was in the context of the foregoing needs that the present invention arose.